fiqhsalatvaliditepiliersarkan
A pillar (rukn) is an element without which the prayer does not stand. Conditions prepare the act (purity, covering, qibla, time); pillars make it up: the opening takbir, the Fatiha and the final salam, then the intention, standing for those able, ruku3, rising, sujud, sitting between the two sujud, the final sitting, stillness and order. Leaving a pillar on purpose invalidates the prayer; forgetting one requires making it up.